1. Field of the Invention
The invention relates to equipment for manufacturing wire products, and more particularly to nonslip multi-pass wire mills.
The invention can be used for drawing wire from any metal preferably of a diameter smaller than 4 mm.
2. Description of the Prior Art
There are known many types of wet wire mills with both coaxial blocks--either stepped or of equal diameter--and blocks arranged in series. These mills operate with slippage of wire on the blocks and are equipped with systems for supplying process lubricants which are emulsions of various compositions.
For example, low-carbon steel wire is drawn, as a rule, using a water emulsion of a mineral oil and of a soap. This emulsion tends to thicken and segregate, and before drawing can be started, the emulsion is to be heated to an optimum temperature of the process, i.e. to a temperature between 40.degree. and 60.degree. C., and thoroughly stirred.
This explains why wire-drawing fluid supply systems are provided with various types of heaters, such as electric heaters or coiled pipes with circulating heating agents which are usually steam or hot water, built into wire-drawing fluid tanks.
Prior-art multi-pass wire mills also include series-arranged blocks with group actuation from an electric motor through gearings. A liquid process lubricant is supplied to a protective casing-bath and to die holders from a separate pumping station to lubricate blocks and dies. Lubricant storage vesses are three roll-out tanks fitted with electric heaters and cooling devices. Gearing and bearings are lubricated by respective circulating liquid lubricants from another pumping station. All the blocks are provided with internal water cooling.
In these mills, a process lubricant is heated by electric heaters and stirred to a homogeneous condition by circulating it by the pumping station through a closed circuit: tank--pumping station--bath--tank (see, for example, Novye skorostnye stany dlya volocheniya aluminievoi katanki (New high-speed mills for drawing aluminium rod), E.L. Shkol'nikov et al, Elektrotekhnicheskaya promyshlennost', ser. kabel'naya tekhnika, 1976, vyp. 11 (141), Moscow, INFORMELEKTRO, pp. 10-12.
Special-purpose electric heaters for the lubricating fluid complicate the design of the mill, whereas a plan circulation of the lubricating fluid through the system fails to emulsify adequately and homogeneously the lubricating-and-cooling fluid.
Another known wet wire mill is one having a system for supplying an emulsified lubricant, the system comprising a pump which draws the emulsion from an oil sump of the wire mill and delivers it to a service tank. A circulating pump sucks the emulsion from the service tank and forces it through a heater and a cooler to supply it to die holders with dies and to blocks. The system also incorporates temperature regulators, a plurality of valves, filters, pressure gauges and thermometers.
Prior to drawing, the heater and the pumps are energized to circulate the lubricant and to heat it to the optimum drawing temperature (35.degree. to 40.degree. C.). Once this temperature is attained, the mill is started, whereas the heater is de-energized and a cooler is started to extract heat transmitted to the lubricant by a workpiece being deformed (see, for example, Wolfgang Teller, Duisburg, and Gunther Schonauer, Kierspe, FRG, Plant for the cooling of lubricants during the drawing of aluminium wire, Wire World International, Dusseldorf, FRG, 1972, v. 14, III/IV, no. 3, pp. 65-66).
However, the quality of the lubricating fluid in this mill is poor, and mill design is complicated by additional units such as heaters.
The closest in design to the present invention is a nonslip multi-pass wire mill consisting of two bed-mounted units with coaxial blocks actuated by adjustable multi-turbine torque converters driven by two electric motors. The torque converters comprise rotors which circulate the fluid through the chambers thereof to transmit motion to the blocks through turbine wheels, and power-operated valves which can cut off emulsion flow and adjust the power input to the blocks.
Die holders with dies are placed in a bath set on a mill bed. The bath also accommodates the blocks which take up wire from respective dies (see, for example, Application No. 54-121264, Cl. B 21C 1/08, filed in Japan in 1979).
In this mill, wire is drawn according to a standard procedure, the process lubricant being soap powder poured by hand into soap-boxes of the die holders.
The main problem in attaining high drawing speeds in this mill is the intensive heating of wire, poor extraction of heat and rapid wear of the dies because the hot wire burns out the lubricant and so impairs lubrication.